APX280M Power System Amplifier
2
• Gain Control - This allows you to set the nominal operating level of the
amplifier. The amplifier's range, 250mV to 2.5V for RCA inputs or 500mV to
5V for speaker level inputs, can accommodate input levels from virtually any
brand of source unit.
• Bass Boost Control- The amplifier also features a "high-Q" (i.e. narrow
frequency band) Bass Boost circuit. It acts much like an equalizer, with
adjustable gain (from 0 to +18dB) fixed at 45Hz. Use this feature to tune low
frequency audio response to compensate for a less than ideal subwoofer
enclosure design. The added boost produces rich, full bass tones that are
normally difficult to reproduce in the car audio environment. NOTE: If Bass
Boost is undesirable, set Bass Boost to 0dB.
High-pass/Low-pass Filter Controls
• Frequency (Hz) Selection Control - The crossover frequency is fully
adjustable between 55Hz and 5500Hz (via the Crossover Frequency Multiplier)
for a wide range of crossover points. Use this feature, along with your speaker
manufacturer's recommended crossover frequencies, to quickly design a more
advanced system (see Applications on page 6) NOTE: If the X-Over Mode
Switch is set to OFF, varying the Freq (Hz) Control will produce no effect.
• Crossover Frequency Multiplier Switch - When engaged, this switch
increases the crossover frequency by a factor of 10. Example: If the Freq (Hz)
dial is set for 240 Hz, pushing in the Multiplier Switch changes the setting to
2400 Hz.
• X-Over Mode Switch - This switch is equipped with a 12dB per octave
electronic filter for precise frequency attenuation with minimal phase
distortion. The steep crossover slope keeps midrange tones out of the
subwoofer and thereby eliminates an unnatural "nasal" tone quality in the audio
system. A filter is activated by sliding the X-Over Mode Switch to either LP or
HP.
• Input Mode Switch - This switch allows you to set the input mode. Stereo
input allows full left and right stereo operation. Right (bridged) input allows
single channel input for bridged operation. This is especially useful in high-powered
systems when using one amplifier for each subwoofer/speaker. L + R
(sum mono) allows a stereo input to be summed into a mono output.
• Speaker Level Inputs - These provide connections for a high-level stereo
source. In addition, these connections are provided for installations where the
source unit's RCA outputs are unavailable.
WARNING: When using the speaker (high-level) inputs, the Black wire must
be grounded at the Radio. Failure to do this will result in noise and improper
operation.
